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Pollutants

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As the popularity of recreational boating has increased, more research has been done to determine the impacts. Results from the U.S. Environmental Protection Agency (EPA), indicate that pollution from boat engines has been underestimated for a long time.

One visible impact of boating on lakes is the presence of petroleum products on the water surface. The iridescent sheen on the water’s surface comes from spills, leaks, and the operation of conventional carbureted two-stroke engines. In calm conditions, just one pint of spilled oil can create an oil slick over an acre of a lake’s surface. Petroleum products that end up in water don’t just disappear with time. They may evaporate, drift to other areas, sink into the sediments, dissolve in the water, or be absorbed by living organisms.  Wind and waves push residual gasoline and oil into the shallows where it can accumulate in the sediments and enter the food chain.

While the focus of lake pollution from motorized watercraft is usually on gasoline and oil (hydrocarbons), there are other pollutants of concern. Metals, bilge contaminants and wastewater also contribute to water quality concerns for the lake.  Finding ways to minimize our impacts on the lake environment starts with preventing the introduction of these pollutants from the start.

Petroleum Pollutants

Benzene, toluene, ethyl benzene, and xylene (BTEX) are potentially harmful compounds found in gasoline.  The City of Bellingham has detected low levels of these compounds in Lake Whatcom.  Studies conducted at Lake Tahoe, another multi-use drinking water reservoir, have associated a direct link in the presence of BTEX with intense levels of boating activity on the lake.

Polycyclic aromatic hydrocarbons (PAH’s) react with ultraviolet sunlight, breakdown into toxic substances and attach to suspended particles and sediments.  PAH’s can stay in the sediments for years and fish and bottom-dwellers ingest them long after they are spilled or washed into the system.

Methyl tertiary butyl ether (MTBE) is a fuel oxygenate used in areas with poor air quality to allow gasoline to burn cleaner.  It has been tentatively classified by the EPA as a possible human carcinogen.  MTBE is currently not produced in Whatcom County and has not been detected in Lake Whatcom, but has been banned or led to boating restrictions in reservoirs in California.

Many boats have a bilge. It is the lowest point under the boat deck where water, oil, fuel, antifreeze, and hydraulic fluid may collect before the automatic bilge pump takes over and sends them overboard.  A manual override can stop the accidental and illegal pumping of contaminated bilge water. Always check the bilge for contaminants before you pump.  Use absorbent pads in the bilge to soak up petroleum products before they go overboard. This simple action can help protect the lake and help you avoid a fine for the illegal discharge of contaminated bilge water.

Bilge cleaners can also cause environmental problems and cannot be pumped overboard into Lake Whatcom. Many bilge cleaners are not biodegradable or non-toxic. Even if the cleaner is environmentally safe, once it has combined with any petroleum product, the resulting mixture becomes harmful to the environment. The best option is to clean the bilge when the boat is out of the water and away from the lake. 

Smaller boats and inboard/ outboard may not have a bilge. These boats usually have a well for the fuel container. Place an absorbent pad under the gas tank in the well to prevent small leaks or spills from becoming large slicks.

Some boaters use dish soap in the bilge or to disperse small spills on the water’s surface.  These actions are harmful to the environment and illegal.  It may appear that the petroleum just “disappears” with the addition of soap.  Actually, the petroleum product becomes emulsified by the detergent.  This means that the soap breaks the oil into invisible droplets that are difficult to contain and clean up which is more damaging to aquatic life.  Link to Hydrocarbons

Although most metals will sink and accumulate on the floor of the lake and not remain suspended in the water column, they do remain in the sediment and can attach to particles that are then distributed throughout the water.  Wildlife indirectly ingest metals as they take in sediments while feeding.  The pollutants accumulate in their tissues and are not excreted.  Therefore, as the food chain continues and larger species eat smaller ones, the levels of toxins in the tissues continue to increase.  This process, called bioaccumulation, is the reason even small levels of pollutants found in a water test can result in large relative quantities found in fish and other organisms. 

The following chart outlines some of the metals that can end up in Lake Whatcom from the presence of boats on the lake and activities in the surrounding areas:

Boat Sewage

Discharging sewage from your boat is illegal (RCW 90.48.080) and contributes to the degradation of water quality. While it may seem to have little impact at the time, think about what the water might look like if every boater used the lake in this way. If you use a portable toilet, dump it in the appropriate station on shore. If your boat has a holding tank, pump it out regularly to avoid an overflow, but not overboard.

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